Source : Webster's Revised Unabridged Dictionary (1913)

Provable \Prov"a*ble\, a. [See {Prove}, and cf. {Probable}.]
   Capable of being proved; demonstrable. -- {Prov"a*ble*ness},
   n. -- {Prov"a*bly}, adv.

Source : WordNet®

provably
     adv : in an obvious and provable manner; "his documentary sources
           are demonstrably wrong" [syn: {demonstrably}, {incontrovertibly}]